Washer fluid pumps of said type are, in modern windshield washer systems, often mounted on a washer fluid tank and are known from practice. The ventilation opening serves for climate and pressure compensation of the housing which at least partially holds the electric motor, and is for example formed as an open end of a ventilation duct which is guided straight through the housing. Here, the ventilation opening must be large enough to permit an infiltration of air into the housing and a discharge of air out of the housing. An excessively small ventilation opening tends to become blocked, which often leads to a pressure build-up and to damage of sealing elements between the electric motor and the pump stage or to foreign objects being sucked into the interior of the electric motor.
An excessively large opening, in contrast, leads to an infiltration of spray water into the electric motor. In both cases, the washer fluid pump can be damaged and spontaneously fail.
It has already been considered to guide the ventilation duct radially out of the housing and to arrange a bulkhead in front of the ventilation opening. This however leads to very complex production of the washer fluid pump.